We have completed the analysis of three adenine nucleotides, calculated the function of adenylate energy charge (AEC), and found it directly related to the percent viable cells in a pure culture of bacteria. Use of AEC analysis of viable cell mass is being assessed in dental plaque samples obtained from monkeys which have been treated with antiplaque agents. Protein content of plaque, conventional viable counting on bacteriological media, fluorescent antibody analysis for streptococci and actinomyces, and adenine nucleotide and AEC values are being compared. A computer program has been written to do the calculations for the nucleotide analyses.